Method of producing phosphorus-containing polymers from diphosphonous acid esters and organic dihalogen compounds



Unite States: Patet 3 171,818 METHOD OF PRODIJCING PHOSPHORUS-CON- TAINING POLYMERS FROM DIPHOSPHONOUS ACID ESTERS AND ORGANIC DIHALOGEN COMPOUNDS i Manfred Sander, Frankfurt am Main, Germany, assignor to Armstrong Cork Company, Lancaster, Pa., a corporation of Pennsylvania No Drawing. Filed Sept. 6, 1961, Ser. No. 136,164 3 Claims. (Cl. 2602) Various proposals have already been made for producing phosphorus-containing polymers by the polymerization of unsaturated organic phosphorus compounds. The phosphorus in such polymers is contained in side groups while the main chain is a hydrocarbon chain. The present invention, on the other hand, is directed at the production of polymers which contain phosphorus in the main chain, the phosphorus'being connected with the hydrocarbon radicals of the main chain only by P--C bonds.

The polymers in accordance with the invention can be prepared by reaction of disphosphonous acid esters with organic dihalogencompounds in accordance with the mechanism R and R" are bivalent organic radicals, R is a monovalent organic radical.

Diphosphonous acid esters which are suitable for this purpose are compounds of the type in which in each case at least one R' group on each phosphorus atom is an alkyl group. The bivalent radical R can bean aliphatic, aromatic or araliphatic hydrocarbon radical. Examples of such suitable compounds are tetraethyl-tetramethylene-diphosphonite, tetraethyl pentamethylene disphosphonite, tetraethyl-h'examethylenediphosphonite, P,P'-diethyl-P,P-diphenyl-hexamethylenediphosphonite, ethyl-p-phenylene-diphosphonite, and tetrabutyl-hexamethylene-diphosphonite. These compounds can be prepared for instance by reaction of the corresponding organic dimagnesium halides with dialkyl-halophosphites.

As dihalo-compounds, there can be used halogen compounds, the halogen atoms of which are bound to aliphatic hydrocarbon radicals, preferably those the halogen atoms of which are bound to primary carbon atoms. Examples hereof are 1,4-dichlorobutane, 1,6-dichlorohexane, 1,2- dibromomethane, 1,4-dibromobutane, fl, 8'-dichlorodiethyl ether, fi,fl-dichlorodiethyl sulfone and p-xylylene dichloride.

If it is desired to obtain linear products, the diphos phonous acid ester is mixed with the dihalogen compound in a molar ratio of 1:1 and heated with the exclusion of oxygen until the splitting off of alkyl halide commences. In certain cases, the reaction starts up very vigorously. In this connection, it is advisable to carry out the reaction in an inert solvent, for. instance toluene, xylene, dibutyl ether, or nitrobenzene, in which connection the heat of reaction can be better removed. The reaction in general starts at about 100 to 140 C. In order to complete it, one heats toward the end of the reaction to about 150 to 180 C., possibly distilling the solvent off. The products can however also be separated from the solvent by precipitation with a non-solvent such as benzene hydrocarbons or by freezing out.

The products prepared in this manner are viscous oils,

tetraethyl-ethylene-diphosphonite, tetrasoft masses, or resins of low melting point, depen on the constitution of the components used. Their cl ical structure corresponds to the formula:

xiiaialx Le... a. J.

in which the terminal groups X are halogen atoms anc phosphor-organic groups.

The substances therefore are esters of polyphosph acids. They can be converted into the free polyphosph acids by boiling with acids or alkalis. No splitting of main chain occurs upon this hydrolysis since this cl only has PC bonds aside from CC bonds. The stances are very stable to thermal degradation. S decomposition occurs only above 250 C. Depending the phosphorus content of the polymers, they are d cultly combustible to non-combustible. They are rea solvent in solvents such as alcohols, chlorinated hyr carbons, ethers, esters and ketones.

A limitation of the chain length of the products car obtained by using one of the components in excess, 01 than the molar ratio of 1:1. In this way, the re can be obtained that the products possess predomina1 either halogen terminal groups or phosphor-organic minal groups.

The linear-polymer products can be cross-linked view of the existing phosphine ester groups to form soluble elastomers. This cross-linkage can be efiec for instance by heating with metal oxides, diamines, phenols, dihalogen hydrocarbons or similar difunctio compounds. Cross-linking can I be eflected at big temperatures, however, even without addition of on linking agents, if the non-cross-linked products still c tain suflicient halogen terminal groups. In these ca: the terminal halogen groups react with the middle ph phonate groups in accordance with the equation o o x i -a-i -m -nn RHal+ OR ORA L proceeds very slowly. If the halogen atom is in alpl position to a benzene ring (benzyl position), the cm linking can occur already at to C. Wh carbonyl halide terminal groups are concerned, the ore linkage takes place already at room temperature or up slight heating, so that when using dicarbonyl chloric for the polycondensation, no linear polymers can be c tained. Furthermore, the velocity of the cross-l-inki reaction depends on the naturexof the halogen and i 3 eases in the sequence Cl Br I. The degree of the ass-linking is finally dependent on the number of halon terminal groups present. By the selection of suitable lrting components, it is possible to produce products liCh can be cross-linked easily or only with difiiculty on further heating. A stabilizing of the linear polynrlensates to thermal cross-linkage can be elfected analogous manner by complete exclusion of halogen -minal groups. This .can be done either by a polyndensation which is as complete as possible, or by bsequen-t reaction of halogen-containing polycondensates th compounds which react with the halogen, for instance osphorous acid esters. I v The cross-linked products are elastic masses or solid tins which become elastic 'in the hot. They are inluble in all solvents and do not become liquid upon ating. By boiling with acids or alkalis, the cross-linked aducts can be converted again into linear polyphosinic acids which are identical to the hydrolysis products non-cross-linked products. The linear polycodensates, depending on their condin of aggregation, can be used as hydraulic oils, lubrints, or lubricant additives, as well as flame-inhibiting pregnating agents. The cross-linked products canbe :d for the production of elastic plastics. The hydrolyproducts of the polycondensates can be used as ionchangers, as complex formers (chelating or sequester- ;agents) and as. thickening agents.

J Example 1 97.8 grams of tetraethyl hexamethylene diphosphonite -.re heated at the boiling point for '4 hours with 52.5 tmsof p-xylylene dichloride in 100 ml. xylene. The per end of the reflux condenser was connected with a tp cooled to -70 C. in which 36.2 gramsof ethyl loride (94.4% of thetheoretical quantity; had collectat the end of the reaction. The xylene' was distilled in vacuum at a bath temperature of 110 to 120 C. \e resultant product'was viscous in the hot, and solidid at room temperature to form a soft, solid, somewhat cky colorless mass, which was soluble in thehot in 1st organic solvents. The substance contained 16.15% osphorus and 0.6% chlorine. The reduced viscosity teasured in 1:1 benzene/tetrachloroethane at 25 C.) s 0.22.

Heating the substance for three hours at 180 to 200 led to a product which is elasto-viscous in the hot, and n in the cold, and proved to be insoluble in all solnts. Products having the same properties were obned from the non-cross-linked polymeric substance by sting for one hour with =1% magnesium oxide at 160 170 C., or by heating for twohours with 1.5% hexaathylene diamine at 170 to 180 C.

[11 another batch, the product obtained after the xylene 1 been distilled off was further heated for 5 hours at 3 to 170 C. As a result of this treatment, the reeed viscosity increased from 0.21 to 0.39, and the crime content dropped from 0.5% to 0.1% This prodcould be cross-linked only at temperatures above 1 C.

in a third batch, the product obtained after the xylene 1 been distilled off was heated with of its weight triethyl phosphite to 140 C. for one hour. The prodremaining after the excess tetraethyl phosphite had :n distilled off, which product was similar in its other perties to the substances which had not been afterated, proved to be resistant to heating up to 250 C., no cross-linking occurred thereby. The product 11d be cross-linked by heating with 1 to 2% magnesium de, hexamethylene diamine or p-xylylene dichloride.

Example 2 5.2 grams of tetraethyl hexamethylene diphosphonite 'e heated with 25.4 grams of 1,4-dichlorobutane withsolvent for 5 hours at 150 to 165 C. and then for 2 hours at 180 to 190 0, 23.6 grams of ethyl chloride (86% of the theoretical yield) being collected. in a cooled trap. The resultant product was a highly viscous colorless oil which dissolved in most organic solvents. It contained 19.2% phosphorus, and 0.9% chlorine. In

benzene/tetrachloroethane, the substance showed a re- Example 3 20 grams of tetraethyl hexamethylene diphosphonite were heated with 11.5 grams of ethylene bromide for 4 hours under reflux to C.), 40% of the theoretical amount of ethyl bromide splitting off. Thereupon the reaction mixture was heated for 1% hours at to C. at 15 mm. mercury, only minimum amounts of ethylene bromide distilling 01f. Theproduct obtained in this manner was a colorless, viscous oil which dissolved in all customary solvents. It contained 0.4% bromine and 19.9% phosphorus. If a sample of this substance is held in the flame of a gas'burner, it decomposes with inflation and burns only shortly before complete carbonization with a weak flame which immediately goes out upon removal from the flame of theburner.

If in this example the ethylester is replaced by 16.5 grams of the methyl ester of hexamethylene diphosphonous acid, there is obtained a similar product (If-content,

22.5%) which is even more difficult to burn than the above product.

Example 4 15.4-grams of tetraethyl hexamethylerie diphosphonite were heated for '10 hours at 140 to 160 C. with 6.76

grams of p,fl'-dichlorodiethyl ether, 65% of the theoreti-.

cal amount of ethyl chloride being split off. The resultant product contained 6.5% chlorine. The substance was heated for an additional 2 hours at 0., whereby Example 5 15.6 grams of tetraethyl pentamethylene diphosphonite were heated for 4 hours under reflux, with 3.75 grams of p-xylylene dichloride in 25 ml. of xylene, 92% of the theoretical amount of ethyl chloride being distilled off. From the xylene solution, the product separated as a semisolid mass upon the addition of 30 ml. of petroleum ether. The substance dried in vacuum at 130 C. contained 0.5% chlorine and in benzene/tetrachloroethane, had a reduced viscosity of 0.25. I In its behavior upon heating with or without cross-linking agents, the substance behaves in the same way as the product described in Example -1, i.e., it could be cross-linked relatively easily.

A similar product is obtained if instead of the pentamethylene diphosphonite, there are used 14.9 grams of tetraethyl tetramethylene diphosphonite.

Example 6 1. The method of producing phosphorus-containing"- polycondensates comprising reacting diphosphonites of the general formula with dihalogen compounds of the general formula in a molar ratio of 1:09 to 121.1 by heating to 100 to 200 C., and distilling off the resultant alkyl halide produced thereby, wherein R and R are selected from the group consisting of bivalent aliphatic hydrocarbon radicals and bivalent aromatic hydrocarbon radicals, R is an alkyl group containing 1-4 carbon atoms, and R is selected from the group consisting of alkyl groups con ing 1-4 carbon atoms and phenyl groups.

2. The method according to claim 1 wherein the tion is carried out in an inert solvent.

5 3. The method according to claim 1 wherein the 1 condensates originally obtained in which R; and R; alkyl groups are converted into a cross-linked, insol condition by beating them to a temperature in the r of 150-250 C. and which is higher than said real 10 temperature.

Morris et a1 Dec. 27, I Hamilton et al Oct. 25, I 

1. THE METHOD OF PRODUCING PHOSPHORUS-CONTAINING POLYCONDENSATES COMPRISING REACTING DIPHOSPHONITES OF THE GENERAL FORMULA 